The present invention relates to an improved depth gauge for a cutter device.
Cutters for endless cutter devices movable along a path for cutting a kerf in a work piece, such as may be found in a saw chain for cutting wood, generally have a cutter portion with a leading cutting edge and a depth gauge portion spaced forwardly of the cutting edge to control the depth of cut taken by the cutter. The depth gauge is instrumental in producing efficient cutting and reducing the possibility of kickback during operation of the saw on which the chain runs.
Depth gauges in the past generally have included a single thickness of cutter material which extends upwardly in a region spaced forwardly from the cutter edge as disclosed in Silvon U.S. Pat. No. 4,353,277. Others have included bent over depth gauge portions such as disclosed in U.S. Pat. Nos. 5,085,113 and 4,989,489 to Pinney, U.S. Pat. No. 4,911,050 to Nitschmann and U.S. Pat. No. 4,841,825 to Martin.
The single thickness upright depth gauge as illustrated in U.S. Pat. No. 4,353,277 may have a tendency to dig into the work piece and not provide consistent cutting depth control. Further it is less stable than a bent over depth gauge. The bent over depth gauges illustrated in U.S. Pat. Nos. 4,911,050; 4,989,489; and 5,085,113 generally have substantially rectangular configurations as viewed in plan, and are susceptible to breakage.
An object of the present invention is to provide a novel depth gauge leading a cutter edge which overcomes the disadvantages of prior devices.
It has been found that prior cantilevered bent over depth gauges may be subject to failure in the region of the bend line, or juncture section, joining the cantilevered depth gauge plate to the body portion of the cutter. Failure often will begin as cracks on the inner side of the bend at the opposed front and rear free ends of the bend. These cracks then migrate inwardly toward the central region of the bend in the depth gauge, producing failure.
It has been discovered that two design modifications may be made to minimize, or eliminate, this problem. First is by producing a larger radius juncture section joining the body portion and depth gauge plate portion. Second, it has been found that benefits arise by deforming the depth gauge material in the bend, or juncture region, inwardly toward the center of bending in a region intermediate the forward and rearward ends of the depth gauge.
The deformation may be in the form of an indentation in the laterally outwardly facing side surface of the juncture section which deforms material inwardly on the underside of the cantilevered depth gauge plate portion. This shifts the neutral axis of the juncture section inwardly toward the center of bonding, such that the stresses will be significantly reduced at the inner sides of the bend at opposed free ends of the bend to eliminate or minimize previously-experienced failure.
An added benefit and advantage occurs from providing an indented deformation on the laterally outwardly facing side of the juncture section. Added side plate relief is provided on the depth gauge forwardly of its rearwardmost edge to reduce drag and friction in the kerf cut, thus to provide more effective and efficient action for the depth gauge.